1. Field of the Invention
The present invention relates to a storage control system ensuring the reliability of information stored in a computer system and, more particularly, it relates to a storage control system having double memories, a plurality of clusters, and double global storage units to ensure a reliable and high speed processing of information in the computer system.
2. Description of the Related Art
In a conventional computer system having at least a main storage unit (MSU), a memory control unit (MCU) and processors (CPU's), which stores information from an external stage in the main storage unit, the same information is written to two different areas in the main storage unit, to ensure the reliability of the stored data and to guard against an accidental fault occurrence in the memory (i.e., double-writing). In this case, the information is first stored to one area in the main storage unit, and then the same information is stored to another area in the same main storage unit. Therefore, even if the first stored information is destroyed by an accidental fault, the second stored information is maintained in the other area, and thus the reliability of the information stored in the memory can be ensured.
In the conventional computer system, however, the overall time necessary for storing the information in each of the memory areas in the main storage unit is doubled, and accordingly, this conventional method impedes a high speed processing in the computer system.
A computer system constituted by a plurality of processors (i.e., a multiprocessor system) is known, wherein the plurality of processors is divided into a plurality of groups, each of which is called a "cluster", for a cluster control, and control of an access between processors is performed through each cluster and the global storage unit, for a high speed processing of the information. Accordingly, the multiprocessor system is constituted by a plurality of clusters and the global storage unit, and each cluster comprises a local storage unit, a memory control unit and, for example, four processors operatively connected to the memory control unit.
In the multiprocessor system, the double-writing of the information in the memory must be used to ensure the reliability of the stored information.
Nevertheless, it is impossible to ensure both a high reliability and a high speed processing of the information in the conventional computer system.